DETECTION AND QUANTIFICATION OF STEEL AND COMPOSITE CORROSION WITH SMART CEMENT AND POLYMER COATING MATERIALS
Corrosion is the primary factor affecting the longevity and reliability of all the infrastructures supporting the oil and gas industries that transport crucial energy, highway, buildings and water sources throughout the world. The average annual corrosion-related cost in the United States only is estimated to be $7 billion to monitor, replace, and maintain these assets. Corrosion can be occurred in any material because of reaction with its environment. Various types of coatings are applied to protect steel structures from corrosion.
In this study, a new non-destructive testing method that can be used to detect and quantify the presence bulk and interface was developed. The new method uses the changes in electrical properties of the bulk material and the interfaces to quantify the corrosion. Using this method, the changes in the bulk electrical resistivity of steel specimens were quantified in three principal directions. Corrosion study on steel specimens in dry-air condition, salt and acid solutions were quantified using the new electrical method and the bulk resistivity changes were determined in the three principal directions and were of the order of 1000% compared to the weight change of about 2%. Also, a new material parameter, combining two electrical properties, has been developed to quantify the surface and interface corrosion. Using the new surface corrosion parameter, the corrosion in the steel specimens exposed to various chemical solutions has been quantified and the changes were in the range of 10% to 1800%.
Smart cement and smart polymer composite highly sensing piezoresistive coating materials were developed and used in the evaluating the corrosion in steel-smart coating composites. The composites were exposed to various chemical environments and the changes in the electrical properties at the steel-coating interface and bulk coating materials were quantified using the new electrical parameters. Over period of one year, the change in the interface corrosion for the non-corroded steel-coating composite exposed in various environmental conditions varied from 0% to 19,600% and for the corroded steel-coating composite exposed in various environmental conditions varied from 27% to 145,000%. The property changes in the smart coatings used to protect the corroded steel was in the range of 2,900% to 11,400%, in smart cement, 57% to 310% in smart polyester, and 24% to 62% in smart polymer concrete.
The interface corrosion concept was also verified in the large model and field model tests simulating the cemented oil wells. The interface corrosion parameter in the field model was comparable to the surface corrosion in steel composite specimens exposed to similar conditions in the laboratory.